Conventionally, a typical image forming device using an electrophotographic scheme, such as a copying machine, a facsimile, or a printer, has a plurality of developing devices disposed opposite to an image carrier to keep developing agents mixed with predetermined types of toner respectively. By means of the developing devices, the image forming device visualizes a latent image formed on the image carrier. A supplementary toner container, such as a toner cartridge or a toner bottle, is attached externally to a toner supply section of the developing device so as to supply supplementary toner, for example, during maintenance.
It is suggested that an erroneous attaching prevention mechanism should be included in such a supplementary toner container to prevent a supplementary toner container that is unsuitable to the image forming device from being erroneously attached to the device main body of the image forming device. For example, Japanese Laid-Open Patent Application No. 4-1682/1992 (Tokukaihei 4-1682: published on Jan. 7, 1992) discloses such an erroneous attaching prevention mechanism that a bar code reader or other information reading means provided to the toner supply section so as to read a bar code information shown on the toner cartridge activates a misinsertion prevention shutter based on the result of the reading.
Further, a popular, well-known suggestion is such an arrangement that the supplementary toner container is provided with an information storage medium, such as a non-volatie memory, so as to, when attached to a toner supply section, constitute an electric circuit with a developing device and transmit the information stored in the supplementary toner container to the developing device or the device main body by means of electric signals to form a basis on which a decision is made to prevent erroneous attaching.
However, to apply the erroneous attaching prevention mechanism disclosed for use with a toner cartridge in Japanese Laid-Open Patent Application No. 4-1682/1992 (Tokukaihei 4-1682) to an image forming device having a plurality of developing devices disposed opposite to an image carrier, each toner cartridge requires a bar code, and each toner supply section requires information reading means, such as a bar code reader; this arrangement inevitably leads to increases in costs.
Further, the bar code shown on the toner cartridge is susceptible to contamination as a result of direct exposure to developing agent and toner, as well as the bar code reader and other optical information reading means are susceptible to contamination by developing agent and toner; the arrangement therefore suffers from bar code reading errors.
The aforementioned method whereby an electric circuit is formed by the developing device and the supplementary toner container provided with an information storage medium, such as a non-volatile memory, to transmit the information stored in the supplementary toner container by means of electric signals, renders connection points susceptible to contamination as a result of exposure to toner and developing agent, resulting in malfunctioning connection, abrasion, and other undesirable phenomena.